Electrical connector for use in liquid metal



Oct. 7, 1969 HUTTER ETAL 3,471,826

ELECTRICAL CONNECTOR FOR USE IN LIQUID METAL Filed April 4, 1966 42 33411 25 F1 5 a 3i i W 5 Z; 5254/ 23k Z 2;]

d ,J 59 05 ,a Z8 3 6 12 1a 25w 2% jfl United States Patent 3,471,826ELECTRICAL CONNECTOR FOR,USE IN LIQUID IVETAL Ernest Hutter, Chicago,and Harris H. Hooker, Naperville, 11]., assignors to the United Statesof America as represented by the United States Atomic Energy CommissionFiled Apr. 4, 1966, Ser. No. 540,092

Int. Cl. Htllr 3/04, .7/02 US. Cl. 339-94 4 Claims The inventiondescribed herein was made in the course of, or under, a contract withthe United States Atomic Energy Commission.

This invention relates to a sealing arrangement. More particularly, theinvention relates to a seal for keeping liquid metal away fromelectrical connectors for preventing shorting-out.

In certain types of nuclear reactors using sodium as a coolant, it isvery desirable to obtain accurate information on operating conditions inthe reactor, by means of electrical leads extending down into thereactor well below the sodium level. Disconnectible electric connectorsare needed below the sodium level in order that easy access may be hadto fuel units in the reactor requiring replacement. The seal of thepresent invention may, inter alia, be employed to keep sodium away fromthese electrical connectors.

In the drawing:

FIG. 1 is a longitudinal sectional view of an assembly to which thenovel sealing arrangement of the present invention is applied;

FIG. 2 is a transverse sectional View taken on the line 2-2 of FIG. 1;and

FIG. 3 is a transverse sectional view taken on the line 3-3 of FIG. 1.

As shown in FIG. 1, an outer member comprises a tube 11 having aninternal shoulder 12 provided on its upper side with a flange 13 havinga conical end 13a and an annular groove 14 outward of the flange. Aplurality of passages 15 extends downwardly and outwardly from thebottom of the groove 14 to the outside of the tube 11. The outer member10 also has an inner post 16, whose top is about at the level of the endof the flange 13, and which extends downwardly an appreciable distanceto its base. At said base a transverse wall 17 extends radially outwardto join the inner post 16 with the tube 11 and is spaced an appreciableamount from a lower side 18 of the shoulder 12. The post 16 has anexternal peripheral rib 18a near its base. The post 16 is radiallyspaced from the tube 11 at regions between the wall 17 and the lowerside 18 of the shoulder 12 a greater amount than from the shoulder 12.Thus a sodium trap is formed in the annular space bounded by the post16, the wall 17, the tube 11, and the lower side 18 of the shoulder 12.

An inner member 19 has an external conical surface 20, an annular flange21 extending therefrom, a thin tubular portion 22 adjoining the conicalsurface 20, and a thick tubular portion 23 adjoining the conical surface20 and extending therefrom in the opposite direction from the thintubular portion 22.

The conical surface 20 of the inner member 19 has mechanical sealingengagement with the conical end 13a of the flange 13 on the shoulder 12of the outer member 3,471,826 Patented Oct. 7, 1969 "ice 10, and theflange 21 projects into the groove 14. The thin tubular portion 22 ofthe inner member 19 extends along and closely around the inner post 16of the outer member 10 past the shoulder to a point near the transversewall 17 of the outer member and engages the rib 18a on the post 16. Thethin tubular portion 22 is appreciably spaced radially from the tube 11of the outer member 10 between the wall 17 and the shoulder 12. Thethick tubular portion 23 of the inner member 19 extends along and withinthe tube 11 of the outer member 10 and has axially spaced externalperipheral ribs 23a engaging the interior of the tube 11. Each rib 23ais made discontinuous by a plurality of peripherally spaced slots 23b,as is illustrated in FIG. 3 for the lower of the two ribs 23a.

The inner member 19 is held in the outer member 10 by means of a spring24 and a retainer 25 which has a bayonet connection with the outermember. The spring 24, which acts against a nut 25a adjustablypositioned in retainer 25, yieldingly urges the conical surface 20 ofthe inner member 19 against the conical end 13a of the flange 13 on theshoulder 12 of the outer member 10.

The post 16 of the outer member 10 is hollow and carries an insulator26, which is retained in the post by a snap ring 27. Mounted in theinsulator 26 are a set of male electrical connectors 28, which slidablyengage a set of female electrical connectors 29 mounted in an insulator30. The latter insulator is carried by the inner member 19 and isretained therein by a snap ring 31. Electrical leads 32 coated withceramic insulation extend from the connectors 29 through the innermember 19 and a conduit 33.

A pump 34 is connected to the conduit 33 for supplying argon at a slightpressure through the conduit, the inner member 19, and openings 35 inthe insulator 30 between the thin tubular portion 22 of the inner member19 and the post 16 of the outer member 10, between the thin tubularportion and the tube 11, between the thin tubular portion and theshoulder 12, between the thin tubular portion and the flange 13, andbetween the conical surface 20 of the inner member 19 and the conicalend 13a of the flange 13 to the groove 14. The purpose of thepressurized argon thus fed is to prevent sodium located outside theouter member 10 from finding its way into the space between theinsulators 26 and 30, where it might short out the electrical connectors28 and 29.

The assembly of parts just described may be used for measuringtemperatures in a sodium-cooled nuclear reactor (not shown) havingclosely packed parallel fuel units each consisting of an hexagonalcasing and a plurality of clad fissile rod-like elements positionedtherein. The sodium is pumped through the reactor in a plurality ofparallel paths, one to each unit through the casing thereof and over theelements. For temperature studies in the reactgr core, thermocouples areinserted in one or more of the units, and the apparatus of the presentinvention may be used for connection of the thermocouples. The outermember 11 is an integral or separate axial extension of a unit wherethermocouples are placed. Thus, like the casing of a fuel unit, theouter member 10 has the exterior shape of a hexagon. Two thermocouplewires 36 and 37 of different metals coated with ceramic insulation, areconnected to two electrical connectors 28 and extend therefrom through atube 38 down to the nuclear-reactor core in a manner not shown wherethey have a junction (not shown). Two more thermocouple wires 36 and 37are illustrated as connected to two more electrical connectors andextending down through another tube 38 to another junction in thereactor core. It is to be understood that there may be other sets ofthermocouple wires 36 and 37 to the extent that the size of theinsulators 26 and 30 will permit. A single wire may also be provided ineach tube 38 to test for a leak in a given fuel element. In thisarrangement, there may be 7 to 19 of such single wires, because in onefuel unit there may be 19 fuel elements arranged as one element, a firstring of 6 elements, and a second or outer ring of 12 elements.

The tubes 38, which are of stainless steel, are sealwelded to openingsin a wall 39 extending transversely across the inner post 16 near itslower end. The outer member 10, the inner member 19, the spring 24, theretainer 25 and the conduit 33 are formed of stainless steel.

During operation of the nuclear reactor, sodium is pumped into the fuelunits at their lower ends and leaves these units at upper regionsthereof at the top of the reactor core. This goes on below the level ofthe parts shown in FIG. 1. During reactor operation the level of thebody of sodium being pumped is as indicated by a dash-dot line 40, abovethe lower end of the conduit 33. Because sodium extends up to line 40,it might conceivably reach the mechanical seal formed between theconical surface 20 on the inner member 19 and the conical end 13a of theflange on the shoulder 12 of the outer member 10, by way of the drainholes 15 and groove 14 and by way of the small spaces between the outermember 10, the retainer 25, and the inner member 19. Yet. the sodiumcannot reach the aforesaid mechanical seal, because the argon collectedin the annular pocket formed between the bottom of the annular groove 14and the flange 21 keeps it out and the very narrow space between thegroove 14 and the sides of the flange 21 help to impede the sodium.

When one or more fuel assemblies of the reactor are to be replaced, thereactor is shut down, and the pumping of sodium through the fuel unitsis stopped. The level of the sodium is lowered from the line 40 throughthe conduit 33 to a dash-dot line 41 about at the level of thetransverse wall 17. If the fuel unit to be removed has the parts of FIG.1 formed as its upper extension, it is of course imperative that theconduit 33 be removed before a lifting device can be applied to the fuelunit for removing it from the reactor. If the fuel assembly to beremoved lies elsewhere than directly below the parts of FIG. 1, it ishighly desirable to remove the conduit 33 in order to take it out of theway of the lifting tool as it is being lowered to the fuel assembly tobe replaced.

When the conduit 33 is removed, the inner member 19, spring 24, andretainer 25, which are connected With the conduit, are also removed.When the inner member 19 and retainer 25 are removed, any residualsodium on the outer member may find its way to the inside thereof by wayof the open top thereof of grappling holes 42, one of which appears inFIG. 1. The sodium thus reaching the inside of the outer member 10 willflow into the groove 14 and out through the drain holes 15 or into thelarge trap formed between the tube 11 and the post 16 and between thetransverse wall 17 and the lower side 18 of the shoulder 12. Thus thereis little, if any, chance that the residual sodium reaching the insideof the outer member 10 will find its way to the top of the insulator 26and the electrical connectors 28 either by flowing down thereto or byaccumulating sufiiciently in the aforesaid trap as to overflow it.

The purpose of the ribs 23a on the inner member 19 is to center it inthe outer member 10 and thus to insure that the flange 13 of the innermember readily enters the space within the flange 21 of the outermember. The purpose of the slots 23b in the ribs 23a is to prevent themfrom acting like pistons in pushing sodium .7 4 clinging to the insideof the outer .member 10 toward the sealing surfaces 13a and 20 uponreassembling of the members 10 and 19.

It is understood that the invention is not to be limited by the detailsgiven herein but that it may be modified within the scope of theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An assembly comprising (1) an outer member comprising a (a) tube,

(b) an internal shoulder attached interiorly to the tube and provided atone side with an annular flange and an annular groove directly radiallyoutward of the flange, the flange having a conical end, the outer member:further comprising (c) an internal post having a top about at the levelof the end of the flange, the post being radially inwardly spaced fromthe shoulder and the flange and extending axially to a base located anappreciable distance beyond the other side of the shoulder opposite thesaid one side, the post having near its base an external peripheral rib,the outer member also having (d) a transverse wall extending radiallyinwardly from the tube to the post at the base thereof, the post beingradially spaced from the tube at the regions between said wall and thesaid other side of the shoulder a greater amount than from the shoulder,whereby a sodium trap is formed in the annular space bounded by thepost, the wall, the tube, and the said other side of the shoulder,

(2) an inner member having (a) a conical surface located in matingengagement with the conical end of theflange on the shoulder of theouter member and (b) an annular flange radially outward of the conicalsurface and extending into the groove on the shoulder, the inner memberhaving (c) a thin tubular portion adjoining the conical surface andextending axially in one direction along and around the inner post ofthe outer member to a point near the transverse wall thereof so as toarrange the rib on the post, the thin portion being radially spaced fromthe interior of the tube between the shoulder and the wall, the innermember also having (d) a thick tubular portion extending from theconical surface in the opposite direction to the thin tubular portionwithin the tube and having axially spaced peripheral ribs engaging theinterior of the tube,

(3) a first set of electrical connectors mounted in the post,

(4) a second set of electrical connectors mounted in the inner memberand being engaged with the electrical connectors of the first set uponengagement of the conical surface of the inner member with the conicalend of the flange on the shoulder of the outer member,

(5) a conduit connected with the inner member,

(6) leads to the electrical connectors of the second set extendingthrough the conduit, and

(7) means :for supplying gas under pressure through the conduit betweenthe thin tubular portion of the inner member and the post, between thethin tubular portion and the tube of the outer member, between the thintubular portion and the shoulder, and between the conical surface of theinner member and the conical end of the flange on the shoulder to thebottom of the annular groove in the outer member outward of the flange.

2. The assembly specified in claim 1 and further comprising a firstinsulator mounting the first set of electrical connectors in the post,and a second insulator mounting the second set of electrical connectorsin the inner member and having openings for passing the gas underpressure.

3. The assembly specified in claim 2, the outer member being providedwith drain openings leading to the exterior of the outer member from theannular groove in the said one side of the shoulder.

4. The assembly specified in claim 3, the members being held together ina bayonet connection, the assembly :further comprising a spring foryieldingly urging the conical surface of the inner member against thesaid one side of the shoulder of the outer member.

References Cited UNITED STATES PATENTS 2,248,588 7/1941 Shanklin et a1.174---21 2,376,265 5/1945 Meredith 17421 2,620,029 12/1952 Turechek etal. 33996 MARVIN A. CHAMPION, Primary Examiner I. H. MCGLYNN, AssistantExaminer US. Cl. X.R. 339-117

1. AN ASSEMBLY COMPRISING (1) AN OUTER MEMBER COMPRISING A (A) TUBE, (B)AN INTERNAL SHOULDER ATTACHED INTERIORLY TO THE TUBE AND PROVIDED AT ONESIDE WITH AN ANNULAR FLANGE AND AN ANNULAR GROOVE DIRECTLY RADIALLYOUTWARD OF THE FLANGE, THE FLANGE HAVING A CONICAL END, THE OUTER MEMBERFURTHER COMPRISING (C) AN INTERNAL POST HAVING A TOP ABOUT AT THE LEVELOF THE END OF THE FLANGE, THE POST BEING RADIALLY INWARDLY SPACED FROMTHE SHOULDER AND THE FLANGE AND EXTENDING AXIALLY TO A BASE LOCATED ANAPPRECIABLE DISTANCE BAYOND THE OTHER THE POST HAVING NEAR ITS BASE ANEXTERNAL PERIPHTHE POST HAVING NEAR ITS BASE AN EXTERNAL PERIPHERAL RIB,THE OUTER MEMBER ALSO HAVING (D) A TRANSVERSE WALL EXTENDING RADIALLYINWARDLY FROM THE TUBE TO THE POST AT THE BASE THEREOF, THE POST BEINGRADIALLY SPACED FROM THE TUBE AT THE REGIONS BETWEEN SAID WALL AND THESAID FROM SIDE OF THE SHOULDER A GREATER AMOUNT THAN FROM THE SHOULDER,WHEREBY A SODIUM TRAP IS FORMED IN THE ANNULAR SPACE BOUNDED BY THEPOST, THE WALL, THE TUBE, AND THE SAID OTHER SIDE OF THE SHOULDER, (2)AN INNER MEMBER HAVING (A) A CONICAL SURFACE LOCATED IN MATINGENGAGEMENT WITH THE CONICAL END OF THE FLANGE ON THE SHOULDER OF THEOUTER MEMBER AND (B) AN ANNULAR FLANGE RADIALLY OUTWARD OF THE CONICALSURFACE AND EXTENDING INTO THE GROOVE ON THE SHOULDER, THE INNER MEMBERHAVING (C) A THIN TUBULAR PORTION ADJOINING THE CONICAL SURFACE ANDEXTENDING AXIALLY IN ONE DIRECTION ALONG AND AROUND THE INNER POST OFTHE OUTER MEMBER TO A POINT NEAR THE TRANSVERSE WALL THEREOF SO AS TOARRANGE THE RIB ON THE POST, THE THIN PORTION BEING RADIALLY SPACED FROMTHE INTERIOR OF THE TUBE BETWEEN THE SHOULDER AND THE WALL, THE INNERMEMBER ALSO HAVING (D) A THICK TUBULAR PORTION EXTENDING FROM THECONICAL SURFACE IN THE OPPOSITE DIRECTION TO THE THIN TUBULAR PORTIONWITHIN THE TUBE AND HAVING AXIALLY SPACED PERIPHERAL RIBS ENGAGING THEINTERIOR OF THE TUBE. (3) A FIRST SET OF ELECTRICAL CONNECTORS MOUNTEDIN THE POST, (4) A SECOND SET OF ELECTRICAL CONNECTORS MOUNTED IN THEINNER MEMBER AND BEING ENGAGED WITH THE ELECTRICAL CONNECTORS OF THEFIRST SET UPON ENGAGEMENT OF THE CONICAL SURFACE OF THE INNER MEMBERWITH THE CONICAL END OF THE FLANGE ON THE SHOULDER OF THE OUTER MEMBER,(5) A CONDUIT CONNECTED WITH THE INNER MEMBER, (6) LEADS TO THEELECTRICAL CONNECTORS OF THE SECOND SET EXTENDING THROUGH THE CONDUIT,AND (7) MEANS FOR SUPPLYING GAS UNDER PRESSURE THROUGH THE CONDUITBETWEEN THE THIN TUBULAR PORTION OF THE INNER MEMBER AND THE POST,BETWEEN THE THIN TUBULAR PORTION AND THE TUBE OF THE OUTER MEMBER,BETWEEN THE THIN TUBULAR PORTION AND THE SHOULDDER, AND BETWEEN THECONICAL SURFACE OF THE INNER MEMBER AND THE CONICAL END OF THE FLANGE OFTHE SHOULDER TO THE BOTTOM OF THE ANNULAR GROOVE IN THE OUTER MEMBEROUTWARD OF THE FLANGE.